By Elaine Lies

KURIHARA, Japan, June 15 (Reuters) - More than 1,000 rescue workers including troops searched on Sunday for a dozen people missing after a powerful earthquake rocked northern Japan, killing at least six and injuring over 200.

The 7.2 magnitude quake struck on Saturday at 8:43 a.m. (2343 GMT Friday) in the prefectures of Miyagi and Iwate, a sparsely populated, scenic region around 300 km (190 miles) north of Tokyo, where buildings also shook.

Mountains were carved away by the force of the quake, trees crashed into newly slashed ravines, roads were cut off at cliffs and bridges buckled and broke.

More than 240 aftershocks had jolted the area by Sunday morning, and officials warned there could be strong quakes to come.

Efforts to find seven people believed trapped in a hot spring resort swamped by a massive landslide resumed early on Sunday morning. Five had been rescued on Saturday.

Rescue workers picked their way through debris while scores of others, including soldiers, began carefully crossing a river of mud to get to the two-story inn, whose first floor had completely collapsed, footage from NHK public TV showed.

Homes were littered with scattered and smashed belongings.

"I don't know where we'll go, or what we will do now," said 80-year-old Naoshi Miura, who with his wife Kirino, 76, and their two dogs was airlifted by helicopter from their mountain home.

Six people had been confirmed dead, and NHK said 224 were injured.

About 300 people spent the night in evacuation centres and some 340 households were without electricity, officials in Miyagi and Iwate prefecture said. More than 2,500 homes were without water as of Saturday evening, the officials said.

"There's no water and cooking is hard, so we are living on instant food," said 73-year-old Tokue Takahashi, who came to an evacuation centre to get water.

Some 100 people were cut off in remote areas after roads were blocked by landslides, the officials said.

"I couldn't really sleep at all, just a couple of hours. It's so close to where the helicopters take off and every time they landed, the windows shook," said 83-year-old Kaoko Mitsugahara, at an evacuation centre near a school where a steady stream of rescue helicopters were taking off and landing.

"We can't get home at all. It's all broken up."

Many others, however, had returned home after spending the night in the make-shift evacuation centres.

As is often the case when natural disasters strike rural Japan, many of those affected were elderly, some living alone.

"If people live alone, it's a worry for their health," said Minoru Suzuki, a 77-year-old volunteer medical worker.

"Stress is a big problem."

Experts said the scope of the quake was far smaller than the one that hit China a month ago and the region's sparse population and Japan's stricter building codes had also limited the damage.

Earthquakes are common in Japan, one of the world's most seismically active areas. The country accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater.

In October 2004, a magnitude 6.8 earthquake struck the Niigata region in northern Japan, killing 65 people and injuring more than 3,000. That was the deadliest quake since a magnitude 7.3 tremor hit the city of Kobe in 1995, killing more than 6,400. (Additional reporting by Hugh Lawson and Linda Sieg; Writing by Linda Sieg; Editing by Jerry Norton)

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